English

Discusses sources of nitrogen dioxide in indoor air in houses in the Netherlands. Measurements were made in a random sample of about 300 houses with a geiser in Enschede and Arnhem. A second sample of 326 houses in Ede were measured a year later. The Dutch outdoor standard for concentrations of nitrogen dioxide was regularly exceeded indoors.

The influence of indoor nitrogen dioxide exposure on respiratory symptoms of school children was investigated in a case-control study. The election method used was useful in obtaining symptomatic children, but insufficient indefining cases and controls without additional information. No relationship between indoor NO2 and respiratory symptoms was found. Bias may have been present, especially because of the high mobility of the study population. Attempts to estimate historical exposure were inaccurate.

A small, personal monitoring study was performed in a subpopulation (14 families) of a case-control study on the relationship between indoor nitrogen dioxide exposure and respiratory diseases of school children. 

Indoor NO2 concentrations were measured in the kitchen, the living room and bedroom of 612 houses in two different areas in the Netherlands. In asub-sample, personal exposure of the housewives to NO2 was measured. NO2concentrations indoors depended on the presence or absence of (un)vented gas appliances. Personal NO2 exposure was only different between the two areas in the group with the lowest indoor concentrations. It was concluded that with respect to NO2 exposure it is impossible to categorize groups without accounting for gas appliances inside the house.

Describes use of water tanks to simulate two- and three-dimensional natural ventilation air flows through open doors and windows. Density differences are produced by dissolved salt. The technique is inexpensive and visualisation of flows through complicated patterns of doors and passageways, and even separate floors can be easily set up.

Describes the principal causes of condensation in dwellings in the UK. Monitoring the existing environmental conditions within a building, plus a structural and tenant survey, is required to determine the correct cure. Theinstrumentation and techniques are listed, and some solutions are suggested.

Describes evaluation of two integrated heating and ventilating systems, one a modified warm air system and the other a modified mechanical ventilation system. From the technical viewpoint the systems were found to be efficient. However it remains to be seen whether mechanical ventilation systems with heat recovery including flue heat recovery can be justified in economic terms.

Describes construction of two townhouses taking into consideration several technical issues: 1) limiting of indoor sources of contamination, 2) limiting contaminants off-gassed from construction materials, 3) limiting entry of exterior contaminants, 4) control of occupant generated contaminants by mechanical and by natural ventilation, and 5) control of indoor humidity The units are to be monitored over the next two years.

Reviews ways of reducing energy loss due to infiltration while maintaining air quality. Results from existing houses are presented. Describes a method to reduce the average air flow coefficients of the envelope to minimum required values and to determine the heat criteria of various ventilation systems.

Computer programs INFILS and ACFES2/R have been developed for the analysis of industrial buildings' heating loads and energy consumption relating to air infiltration. The heat demand computation results for typical hall structures are presented. It is shown that on windy days with low outside temperatures, total heat losses rose to 180% of basic heat losses. The necessity of developing proper methods for designing, building and testing elements of industrial buildings is emphasized.